package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.Locale;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {

    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;
    @Override
    public Result queryById(Long id) {
        //缓存穿透
        //Shop shop = queryWithPassThrough(id);

        //互斥锁解决缓存击穿
        //Shop shop = queryWithMutex(id);
        //if (shop==null) {
        //    return Result.fail("店铺不存在！");
        //}

        //逻辑过期解决缓存击穿
        //Shop shop = queryWithLogicalExpire(id);
        Shop shop = cacheClient.queryWithLogicalExpire(CACHE_SHOP_KEY, id, Shop.class, this::getById, CACHE_SHOP_TTL, TimeUnit.SECONDS);

        //7、返回
        return Result.ok(shop);
    }
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);//线程池
    public Shop queryWithMutex(Long id){
        //1、 从redis查询商铺缓存
        String shopJson = stringRedisTemplate.opsForValue().get(CACHE_SHOP_KEY + id);
        //2、判断是否存在
        if (StrUtil.isNotBlank(shopJson)) {
            //3、存在，直接返回
            return JSONUtil.toBean(shopJson, Shop.class);
        }
        //判断命中的是否是空值
        if(shopJson != null){
            return null;
        }
        //4、实现缓存重建
        //4.1 获取互斥锁
        String lockKey = LOCK_SHOP_KEY+id;
        Shop shop = null;
        try {
            boolean isLock = tryLock(lockKey);
            //4.2 判断是否获取成功
            if(!isLock){
                //4.3 失败，则休眠并重试
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            //4.4 成功，根据id查询数据库
            shop = getById(id);
            //5、不存在，返回错误
            if(shop==null){
                //将空值写入redis
                stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                //返回错误信息
                return null;
            }
            //6、存在，写入redis
            stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY + id,JSONUtil.toJsonStr(shop),CACHE_SHOP_TTL, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            //7、释放互斥锁
            unlock(lockKey);
        }

        //8、返回
        return shop;
    }

    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }
    private void saveShop2Redis(Long id,Long expireSeconds){
        //1、查询店铺数据
        Shop shop = getById(id);
        //2、封装逻辑过期时间
        RedisData redisData = new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        //3、写入Redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));
    }
    @Transactional
    @Override
    public Result updateShop(Shop shop) {
        if(shop.getId() == null){
            return Result.fail("店铺id不能为空");
        }
        //1、更新数据库
        updateById(shop);
        //2、删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY + shop.getId());
        return null;
    }

    @Override
    public Result queryByType(Integer typeId, Integer current, Double x, Double y) {
        //1、是否需要根据坐标查询
        if(x==null || y==null){
            //不需要坐标查询，按数据库查
            Page<Shop> page = query().eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            //返回数据
            return Result.ok(page.getRecords());
        }
        //2、计算分页参数
        int from = (current-1)*SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current*SystemConstants.DEFAULT_PAGE_SIZE;
        //3、查询redis、按照距离排序、分页 结果：shopId、distance

        //4、解析出id

        //5、根据id查询店铺shop

        //6、返回
        return null;
    }
}
